Minn Kota Power Drive Shaft Length on a ProV 1900

[PJ]

Does anyone out there have a Lund Pro V 1900? I'm trying to find out if a Minn Kota Power Drive with a 54" shaft is long enough or shouldi get a 60"? The Power Drive only measured 48" from the bottom of the bow mount to the center of the prop which seams a little short. Lund recomended a 54" shaft but I dont know if that was a Minn Kota or a Motorguide that measures their shaft from the mount to the top of the motor head.
Thanks,PJ